Electric muffle-furnace.



No. 861,744. PATENTED JULY 80, 1907.

A. L: MARSH.

ELECTRIC MUFPLE FURNAGE. APPLICATION FILED 313.18. 1907.

4 Illll Y 'UNITED STATES I OAL'IEN'I OFFICE.

ALBERT L. MARSH, OF LAKE BLUFF, ILLINOIS, ASSIGNOR TO HOSKINS CO.,

ILLINOIS, A CORPORATION OF ILLINOIS.

OF CHICAGO,

ELECTRIC MUFFLE-FURNACE.

Specification of Letters Patent.

Patented July 30, 1907.

Application filed February 18, 1907. Serial No. 358,001.

p view'of Jthe same in front-end elevation, and Fig. 3, a

section taken at the `line 3 on Fig. 2, viewed in the direction of the arrow and enlarged.

The permanent parts of my improved furnace comprise a base 5, of insulating material, a post `G rising vfrom the base, and a metal housing 7, for the mutiie, preferably of the cylindrical shape represented, supported in horizontal position on'the post and having one end closed by a head 8 containing a central opening 9, and provided on its opposite end with a hinged door 10 of metal having an inner facing 11 of heat-insulating material, such as'asbestos fiber.A The door is hinged at a tongue l2 projecting from its lower end, on a bearing 13 depending from 'the housing ,near one end, against which bearing the inner end of the tongue abuts to limit opening of the door to a horizontal position, at which the abutting of the tongue sustains it to adapt it to serve as a shelf, as shown of the door by dotted lines in Fig. 1, representing it in its lowered position.

The muiile consists of an inner tube 14, composed of talc, fused magnesia or other suitable refractory material, about which is coiled a conducting wire l5 of a high degreeiof electrical resistance, and being to that end a resistance element preferably' of the kind covered by Letters Patent of the United States No. 811859, granted to me February 6, 1906; a tubular shell 16 of refractory material, such as 'fire-clay, surrounding the tube 14, with silica 17, vor other heat non-conducting material, packed between the two tubes; a head or disk 19, preferablyof asbestos fiber, closing the inner end of the muiiie, and a head or disk 20 covering the outer end thereof and like the disk 19 except that it contains a central opening 21forming the mouth of the inutile. Rods passing at intervals lengthwise through the mufllestructure, and one of which-is shown at 22, fasten the heads 19 and 20 in place.

The ends of the coil 15 connect with terminals 23 and 24, respectively, rigidly fastened to project from the .head 20 near its center, and each being `split longitudi- 25, of insulating material, containing metallic sockets 2G, 27, connected with one end of a iiexible conductor 28 provided on its opposite end with a suitable plug (not shown) adapted to be connected with an kincandescent-electric-lamp socket, or other source of current supply. The splitting of the terminals renders them resiliently compressible,` whereby when the head 25 is applied to them t0 receive them into its sockets the head bears against the housing-head 8 about the opening 9 therein, and the split terminals bind the head 25 frictionally with a degree of firmness which tightens the muffle in place within the housing.

The described construction adapts the muflle, upon introducing it into its housing, to be quickly and readily put into condition for use, since all that is required to that end is to apply the head 25 to the terminals 23, 24; and the matter of releasing the terminals, by withdrawing the head 25, to free-the muiiie and permit its withdrawal, is effected with equal facility. v

The illustrated cylindrical form of the housing and mule is the preferred form thereof because it enables insertion of the muiile into the housing without reference to any particular way of inserting; and the various details of constuctionshown and describedcontribute to the desired simplicity of the structure and to facility in using it. v l

What I claim as new and desire to secure by Letters Patent is- 1. In an electric Inutile-furnace, the combination of a housing having a head at one end provided with an aperture, a inutile removably insertible into said housing and composed of refractory material with an electricalk resistance element containedtherein having terminals on an end of the muie, and an electric coupling-head adapted to engage With said terminals and housing and forming a .removable astener operating to clamp the housinghead between it and the adjacent inutile-end.

2. Inan electric mufiie-furnace, the combination loi? a housing having a headI at one end provided with an aperture, a muille removably insertible into said housing and composed of refractory material with an electrical resistance element contained therein having terminals projecting from an end of`the muilie, and an electric coupling-head having sockets to receive said terminals in frictionally binding engagement and forming s. removable fastener' p' erating to clamp the housing-head between it and the adjacent inutile-end.

4. In an electric niufiie-furnace, the combination ot a 'housing having a head at one end provided with an aperture and a hinged door 'on its opposite open end adapted to be opened to a horizontal `position and afford a shelf, and a muflie removbly-'insertible into said housing, composed vof refractory material '.with an electrical resistance element containedA therein having terminals on an end of the muie, an electric coupling head containing sockets adapted to receive saidterminals in frictionally binding'engagement. and to bear against" the housing-end to fasten the muiile in place. f

55111 an electric mufe-furnace, the combination of a housing having ahead at one end providedwith an aperture, a muliie removably insertible into said housing and composed of an inner tube -of refractory material, an elec-A trical resistance wirevcoiled about said tube, anlouter tube of refractory material surrounding said inner tube and heat non-conducting materiall between said tubes and a head of refractory-material secured on the inner end of said tubes kand `an annular head of refractory material se-y cured on the opposite end of said tubes, terminals of said 4Wire on said 4inner head, and an electric coupling-head -a base, a post rising therefrom, a housing supported in said post having a head at one end vprovided with an aperture and a hinged door on its opposite end, a mutlie removably insertible into said housing and composed of refractory material with an electrical resistance element contained there- Ain having terminals projecting from the inner end of the muflie through said aperture, and an electric coupling-head .containing sockets adapted to receive said terminals in Vfrictonally,binding engagement and to bear against the housing-end to fasten the muile in place.

e ALBERT L.v MARSH.

In presence of- ..T. H.-L.\NDEs,

R. A. SCHAEFER. 

